| | 1 | Author
| Maria Zdanowska-Fnjczek, Malgorzata Grottel, Ryszard Jakubas | Requires cookie* | | | Title
| C1 NQR and l H NMR Studies of Molecular Motions in Guanidinium Salt of Chloroacetic Acid  | | | | Abstract
| Multinuclear NQR and NMR techniques have been applied in order to study the molecular dynamics in [C(NH 2) 3 ](ClH 2 CCOO). The 35 C1 NQR frequency was measured over a wide range of temperature. The experimental results were described by using the theories of Bayer and Brown which take into account the torsional oscillations of the CClH 2 -group of the anion. A study of the proton NMR second moment as well as relaxation times T, and T Xp performed in a wide temperature range revealed an onset of the guanidinium cation reorientation around its two-fold symmetry axis. Activation parameters for this motion were determined. | | | |
Reference
| Z. Naturforsch. 53a, 484—487 (1998); received March 24 1998 | | | |
Published
| 1998 | | | |
Keywords
| NMR, NQR, Molecular Motion | | | |
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| default:Reihe_A/53/ZNA-1998-53a-0484.pdf | | | | Identifier
| ZNA-1998-53a-0484 | | | | Volume
| 53 | |
| 2 | Author
| Masao Hashimoto, Yuko Monobe, Hiromitsu Terao, Haruo Niki, Koichi Mano | Requires cookie* | | | Title
| Phase Transition and Crystal Dynamics of 4-Bromobenzyl Alcohol | | | | Abstract
| For the title compound a phase transition from Phase II to Phase I (low and room temperature phases, respectively) was found at ca. 217 K. The temperature dependence of the 8 'Br NQR frequency and that of the dielectric constant showed anomalies at ca. 195 K that were tentatively attributed to a higher order phase transition. A similar anomaly was found at ca. 218 K for 4-chlorobenzyl alcohol which showed a II-I transition at 236 K. The dielectric dispersion observed for both compounds at low temperatures indicates an excitation of a molecular motion with the dielectric relaxation rate of ca. 1 kHz. The temperature dependence of the sl Br NQR frequencies of 2-and 3-bromobenzyl alcohol, measured at T > 77 K, gave no evidence of phase transition in their crystals. | | | |
Reference
| Z. Naturforsch. 53a, 436—441 (1998); received March 24 1998 | | | |
Published
| 1998 | | | |
Keywords
| NQR, Phase Transition, Molecular Motion, Dielectric Dispersion | | | |
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| default:Reihe_A/53/ZNA-1998-53a-0436.pdf | | | | Identifier
| ZNA-1998-53a-0436 | | | | Volume
| 53 | |
| 4 | Author
| Naohiro Yoshida, Noriko Onoda-Yamamuro, Shin'. Ichi Ishimaru, Keizo Horiuchi, Ryuichi Ikeda | Requires cookie* | | | Title
| Temperature Dependence of 2 H Quadrupole Coupling Constants in 2 H 2 0 and Ionic Motions in Crystalline IM( 2 H 2 0) 6 ] ISnCl 6 ] (M: Mg, Ca), Studied by 2 H NMR and Neutron Powder Diffraction | | | | Abstract
| The temperature dependence of 2 H NMR spectra was measured at 130-430 K on [M(D 2 0) 6 ] [SnCl 6 ] (M : Mg, Ca) (rhombohedral, space group: R3), and neutron powder diffraction on the Mg salt was performed at room temperature. Based on the accurate orientation of D 2 0 molecules in an octahedral cation, spectra with a large asymmetry parameter rj, observed around 200 K, were explained by a model of 180° flip of water molecules. Another motional narrowing observed above room temperature was assigned to a cationic overall reorientation about the C 3 -axis. | | | |
Reference
| Z. Naturforsch. 53a, 473—479 (1998); received October 31 1997 | | | |
Published
| 1998 | | | |
Keywords
| 2 H NMR, Neutron Diffraction, Molecular Motion, Quadrupole Coupling Constant, Spectrum Lineshape | | | |
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| default:Reihe_A/53/ZNA-1998-53a-0473.pdf | | | | Identifier
| ZNA-1998-53a-0473 | | | | Volume
| 53 | |
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